Are any ATOs really safe?

[Reefer Matt]

I use semi automatic top offs. Basically a five gallon bucket as a reservoir, with a Jebao doser dosing fresh water to top off. I also use a gravity feed system from a five gallon bucket with a hole drilled in the bottom, and ro fittings going to a mechanical float switch. The most it can top off is 5 gallons in a malfunction. But I have to manually refill them every three days.

 

[Dinkins Aquatic Gardens]

I think ATOs are a pretty interesting topic, mainly because of the potential risk of flooding your floors from a faulty ATO overfilling your tank.

ATO devices just seem to always bear that risk. Firstly, you will have multiple points of failure. I know many praise the Tunze ATOs, but even here you will still hear a few stories of overfilling the tank.
Many ATOs include a chip-based failsafe, where if the device is turns on the pump for more than a given time frame, it will automatically stop the pump. Or, alternatively, it can detect if a sensor seems faulty. But if any of you work in tech, you also know how often chips can fail (especially the cheap ones used for aquarium equipment). So, single point of failure right there.

I do hear of mechanical ATOs, often gravity fed, which does make a lot of sense, but isnt always an option for those with small AIO tanks, where you dont have enough space for a high quality float valve, as they are quite bulky.

So, are ATOs ever REALLY safe, or is it just a major risk we will always have to take as saltwater hobbyists?
Are there any redundancies or failsafes you can implement to reduce or eliminate the risk entirely?

I really like what Ryan at @Bulk Reef Supply says about the topic. He says that no ATO is safe, but with proper safeguards you ATO can be the safest unsafe thing in your house. I thought it was a great point when he said that your fridge ice maker has less flooding protection than a well designed ATO (with a few additional precautions).

 

[mike550]

@Schmidt Aquatics if my ATO fails it will dump at most 5G RODI into my sump which has the capacity to hold it. On my tank that would create a change in salinity of 0.001 sg

 

[Schmidt Aquatics]

I really like what Ryan at @Bulk Reef Supply says about the topic. He says that no ATO is safe, but with proper safeguards you ATO can be the safest unsafe thing in your house. I thought it was a great point when he said that your fridge ice maker has less flooding protection than a well designed ATO (with a few additional precautions).

It is true that many pieces of hardware in the common household implies a risk: fire hazard with laundry machine, flooding from washing machine or fridge, flooding from clogged sewers, the list goes on.

However, I dont think a lot of people realize how much just 20 gallons of water is on the floor. It is absolutely nuts, and way more than the risk of any other common household hardware. Water damage aint fun. Not to mention saltwater, which is way worse in terms of potential damage than regular freshwater.
Another problem is that the hardware for our tanks need to last while submerged or in proximity to saltwater 24/7. It is not uncommon that this causes failure. For example, water gets into a water level sensor, or algae or bacterial film grows on it, or salt creep will make a float switch useless. Will maintenance fix it? Yes, possibly, but with sensors you might scratch the lense, rendering it ineffective. In general, the biggest risks would be eliminated if for any of these solutions, no hardware can fail in the “on” setting/position, but ONLY off, like a float valve will.

So, yes, some household hardware has less failsafes, but, there is also less implied risk, as it won’t (or atleast shouldn’t) be exposed to such harsh conditions as saltwater.

Also, I dont think many insurance companies will cover damages caused by a tank flooding because of an ATO…

I can think of many risks, but I am also a cybersecurity expert by profession, so maybe thats just my approach

 

[McPuff]

I've had a tunza osmolator for over a dozen years and it never failed. I replaced it with a new osmolator even though it still works fine (backup now!). I consider these pretty safe. They will only run for 3 minutes so in a big system you really can't flood your system. Set it up properly to avoid any siphoning (user error, not equipment failure!) and you shouldn't have any issues. I even have my ATO reservoir auto-refill from the RODI reservoir (float). If anything, the equipment will fail in the safe way... it won't fill if it runs too long. So in this case your sump level will actually drop. Salinity will go up a bit but this seems a lot safer than flooding with freshwater and continually reducing salinity.

 

[stephydawn]

I don't trust many commercially built products (especially if they are made in China) so I build everything myself.
My ATO is gravity fed. I have a 5 gallon bucket above the tank hanging from the ceiling
(This is in my Man cave so it is not obtrusive, but cool looking)

The bucket gets filled from the RO/DI and shuts off by a float connected to an old mercury switch from a vintage thermostat. (mercury switches can't really fail) The float shuts off the electric valve which sends water through the RO/DI.

The water flows by gravity to my float valve on my tank (I don't have a sump)

The water is fed to the tank through a small 1/4" tube with a valve, and the water only flows a little more than the tank needs for evaporation which is about a drop a second.

I have been using this exact set up for over 45 years with no flood yet.
Of course the day is young and anything can happen.

What does it look like? I thought about putting a small gallon reservoir above my 75 gallon AIO and doing something like that

 

[spawn79]

I find the best way to prevent an ATO from going haywire is to put it on a timer. Whether that's a simple mechanical timer, apex or some kind of "smart" plug is personal preference. Probably the most reliable would be a mechanical timer since it flips an actual physical switch.
But my method is to have a once per day 5 minute on/off cycle on a smart plug on my kasa strip. No matter what happens on the ATO it will only have power for 5 minutes per day and no more. Sure, there is a small chance there could be a power cut at that exact time and it could run longer but kasa will catch it and shut it off later.

Doing it this way and having a small pump that won't pump more than a little at a time has been great for me in the past. If there is more evaporation then have multiple cycles. If less is needed then shorten the cycle time.

 

[LJLKRL05]

I think ATOs are a pretty interesting topic, mainly because of the potential risk of flooding your floors from a faulty ATO overfilling your tank.

ATO devices just seem to always bear that risk. Firstly, you will have multiple points of failure. I know many praise the Tunze ATOs, but even here you will still hear a few stories of overfilling the tank.
Many ATOs include a chip-based failsafe, where if the device is turns on the pump for more than a given time frame, it will automatically stop the pump. Or, alternatively, it can detect if a sensor seems faulty. But if any of you work in tech, you also know how often chips can fail (especially the cheap ones used for aquarium equipment). So, single point of failure right there.

I do hear of mechanical ATOs, often gravity fed, which does make a lot of sense, but isnt always an option for those with small AIO tanks, where you dont have enough space for a high quality float valve, as they are quite bulky.

So, are ATOs ever REALLY safe, or is it just a major risk we will always have to take as saltwater hobbyists?
Are there any redundancies or failsafes you can implement to reduce or eliminate the risk entirely?

I have been using the double model from http://www.autotopoff.com/ for years with no issues. Hangs in the sump and has a failsafe float switch to prevent overflows.

 

[Kellie in CA]

I don't put more water in my reservoir than my tank could hold if the ATO were to malfunction.

 

[Snoopy 67]

I have been using a Litremeter for decades. Never an overflow.
The most I have ever had it set was 2 gal/day & the unit is above the supply.
The hose is the only thing that can go & I've gone 3 years on one before replacing it.

 

[vcollins9850]

I use semi automatic top offs. Basically a five gallon bucket as a reservoir, with a Jebao doser dosing fresh water to top off. I also use a gravity feed system from a five gallon bucket with a hole drilled in the bottom, and ro fittings going to a mechanical float switch. The most it can top off is 5 gallons in a malfunction. But I have to manually refill them every three days.

I also use a dosing pump for my top off on 2 tanks. not sure if that is frowned upon but it works on my smaller tanks.
I just calculated how much FW I was replacing each day and set up the doser to replace. I occasionally add a little here or there bc I estimate on the low end.
1. The x1 pump was only $50-60, seemed cheaper than most ATO systems. Been running the pumps for years and never had a failure. And
2. I also have it timed to flush my all for reef outlet after each time it doses.

 

[NewCaliCaptives]

I think safest ATO would be a well maintained float valve gravity fed to an RO reservoi. Leak sensor above that. Amazon has wifi leak detector that will send you a notification, $16.

 

[BZOFIQ]

You can use ATO and add 2 pieces of hardware to make it foolproof.

1. If you have a controller add a float switch that when triggered would switch off the ATO or ATO Pump Outlet.

2. Add a float valve so that once the water fills too high it will mechanically cut off the water (gravity fed, pumped or otherwise)

 

[Paul B]

What does it look like? I thought about putting a small gallon reservoir above my 75 gallon AIO and doing something like that

It looks like a bucket hanging from the ceiling with a 1/4" tube going to a float valve on the tank. The bucket fills automatically from the DIY DI and RO and when the bucket fills the old thermostat mercury switch shuts the water by an electric solenoid valve.

No maintenance and hasn't failed in decades.

 

[Midrats]

Spectrapure Litermeters since the Nineties. Never had one fail. I tell it exactly how much to add. No floats or sensors to fail. No need to turn it off during maintenance. No back-siphoning. It can pump long distances, up to different floors if needed. Perfect for kalkwasser.

 

[BZOFIQ]

Spectrapure Litermeters since the Nineties. Never had one fail. I tell it exactly how much to add. No floats or sensors to fail. No need to turn it off during maintenance. No back-siphoning. It can pump long distances, up to different floors if needed. Perfect for kalkwasser.

Except they are nowhere to be found and now it looks like replacement kits are not available either.

 

[zoomonster]

Just gonna say I'm another that swears by Tunze and never had an issue. However, the one way you can get burned by any ATO is if the pump line is not done correctly, and you end up with a siphon from the ATO container. I had one of the first ATO's (with tube pressure sensor) years ago and it wiped a tank. I usually keep around 48 gallons of RODI water which is enough to wipe just about any tank so always overly cautious (I don't leave my RODI unit on all the time). I have had a couple Tunzes and one just died after about 8 years. Usually, the only issue is maybe the pump eventually dying. I have also seen the optical sensor get fouled before but then the ATO just doesn't run.

 

[BoomerSLO]

I have a series of smart switches that help me automate feeding and ATO. I tell Alexa to start feeding time, it shuts down my return pump (w/ a backflow) and 1 of my 2 wavemakers. My ATO kicks on, fills for 2 minutes up to the sensor, and turns off. I feed, the wavemaker turns back on, then the return pump. I like all of the ideas shared here, we've all feared this if it hasn't already happened. Even if the backflow fails I just have enough headroom in the sump to hold it. My only risk is if the return pump fails, the backflow fails, and the ATO doesn't turn off right after I've filled the 4 gallon reservoir. If all that happens, so be it.

I think for the AIO setups a smart timer that runs once or twice a day for the right amount of time can help to reduce the chance of disaster. You can design your own routines that could even be run by barking at Alexa. Does anyone think an "always on" system is noticeably better from a salinity standpoint? I'm still fairly new.

 

[Schmidt Aquatics]

I have a series of smart switches that help me automate feeding and ATO. I tell Alexa to start feeding time, it shuts down my return pump (w/ a backflow) and 1 of my 2 wavemakers. My ATO kicks on, fills for 2 minutes up to the sensor, and turns off. I feed, the wavemaker turns back on, then the return pump. I like all of the ideas shared here, we've all feared this if it hasn't already happened. Even if the backflow fails I just have enough headroom in the sump to hold it. My only risk is if the return pump fails, the backflow fails, and the ATO doesn't turn off right after I've filled the 4 gallon reservoir. If all that happens, so be it.

I think for the AIO setups a smart timer that runs once or twice a day for the right amount of time can help to reduce the chance of disaster. You can design your own routines that could even be run by barking at Alexa. Does anyone think an "always on" system is noticeably better from a salinity standpoint? I'm still fairly new.

A smart plug with a set timer for how long the ATO can be turned on each day is a great idea, i’ve considered it myself.
I guess the trick would be to time it a little longer than what is neccessary, to compensate for changing evaporation rates due to room temperature, humidity etc.

 

[Midrats]

Except they are nowhere to be found and now it looks like replacement kits are not available either.

I just received a rebuild kit a couple of weeks ago. It did take a couple of months because they were waiting on part. The price was outrageous. Almost $50 with shipping for some tubing, three rollers, and a couple of fittings.